The objective of the proposed research is to determine the role of the intestine in the conjugation of the xenobiotics. The specific aims are to purify a UDP-glucuronic acid transferase which conjugates p-nitrophenol and use antibodies against the enzyme to determine its contribution to the intestinal microsomal conjugation of p-nitrophenol and other xenobiotics. The results will establish if there is more than one UDP-glucuronic acid transferase in intestinal microsomes and if more than one enzyme can use p-nitrophenol as an acceptor.